This invention relates to a trim apparatus for a marine propulsion unit and more particularly to an improved trim control apparatus for the power trim unit of an outboard drive and to an arrangement for automatically changing the trim condition of the outboard drive in response to certain watercraft conditions.
It is a known practice to support a marine propulsion unit such as an outboard drive for movement relative to the transom of an associated watercraft between a plurality of trim adjusted positions. The optimum trim position for the outboard drive can vary depending upon a wide variety of watercraft conditions. There have been proposed fully manual trim apparatus for marine outboard drives wherein the operator can selectively control the trim position. Although such devices have certain advantages, they require the operator's full attention to the setting of the trim position of the outboard drive under all conditions. Frequently, the operator may forget to adjust the trim condition of the outboard drive to the optimum position for the selected watercraft running condition. There have also been proposed a variety of automatic trim control apparatus for marine outboard drives wherein the trim position is automatically set in response to a watercraft running condition. Although such automatic systems have the advantage of not requiring operator control, they are not fully satisfactory. One reason for this is that the watercraft running conditions may vary from instant to instant and if the automatic trim adjuster is responsive to such instantaneous changes, there will be substantial hunting in the position of the outboard drive and this is not necessary nor is it acceptable.
In order to obviate the disadvantages of the purely manual and purely automatic systems there have been proposed a variety of systems in which there is a semiautomatic operation of the outboard drive and its trim control apparatus. Semiautomatic systems permit the operator to set a predetermined trim condition for a given watercraft running condition and when the watercraft reaches that running condition the power trim apparatus is automatically operated so as to move the outboard drive to the preset position These systems have obvious advantageous. It is, therefore, a principal object of this invention to provide an improved semiautomatic trim control apparatus for a marine propulsion unit.
It is a further object of this invention to provide an improved and simplified arrangement for controlling the trim of a watercraft in response to an acceleration and/or deceleration condition.
It is a further object of this invention to provide an automatic trim control apparatus for a marine outboard drive wherein the trim condition is automatically changed when an operator moves a control element for the outboard drive.
For a wide variety of reasons it is desirable to simplify, as much as possible, the controls for an outboard drive. Specifically, it is desirable to maintain separate controls for certain of the outboard drive functions but it is also desirable to position these controls in such a manner that the operator can conveniently operate them without having to detract his attention from the other controls.
It is, therefore, a further object of this invention to provide an improved and simplified control for the trim of a marine outboard drive.
It is a further object of this invention to provide a combined control for a marine outboard drive that permits trim adjustment and another outboard drive control by means of a single-control lever.